Pill-type fluidic devices



' Jan. 14, 1969 P. A. FREEMAN PILL-TYPE FLUIDIC DEVICES Original FiledOct. 22, 1965 Sheet of? FIGSA INVENTOR PETER A. FREEMAN FIG4A M ,52

ATTORNEYS P. A. FREEMAN PILL-TYPE FLUIDIC DEVICES Original Filed Oct.22, 1965 Jan. 14, 1969 Sheet 3 .of5 FIG? FIGBA f VENT? HGQA VENT 1 pJan. 14, 1969 P. A. FREEMAN PILL-TYPE FLUIDIC DEVICES Original FiLedOct. 22, 1965 Sheet 2 m mm 4 5 9 o o 0 H 3 6 B 3 P .1 Ev c 2 D... @M 2EMQ Jan. 1 4, 1969 p. A. FREEMAN 3,422,259

PILL-TYPE FLUIDIC DEVICES Original Filed Oct. 22, 1965 Sheet 4 of 5 Jan.14, 1969 P. A. FREEMAN 3,422,259

PILL-TYPE FLUIDIC DEViCES Original Filed Oct. 22, 1965 Sheet 5 015 H6. WB

United States Patent 3,422,259 PILL-TYPE FLUIDIC DEVICES Peter A.Freeman, Baltimore, Md., assignor to Martin- Marietta Corporation, NewYork, N.Y., a corporation of Maryland Original application Oct. 22,1965, Ser. No. 501,157, now Patent No. 3,362,633. dated Jan. 9, 1968.Divided and this application Aug. 24, 1967, Ser. No. 670,490 US. Cl.235-201 15 Claims Int. Cl. G06m 1/12; G06d 1/00 ABSTRACT OF THEDISCLOSURE Fluidic binary counters use a pill sliding in a slot as adevice for selecting the direction of flow of input counting pulses,along with a bistable fluidic element of either the Coanda type orcomposed of a number of pill-type logic elements. These binary countersmay be provided with AND or NAND devices to form. stages that, whencascaded, provide a reversibly binary counter.

This is a divisional application of Ser. No. 501,157 filed Oct. 22,1965, now patent No. 3,362,633, dated Jan. 9, 1968.

This invention relates to fluidic devices and systems using suchdevices, and more particularly to fluidic devices which employ apill-like control member which is fluid movable to a plurality ofoperative positions.

Pure fluid devices and fluid devices having moving parts generallyemploy a power stream of fluid which may be selectively switched intodilterent output channels by other control fluid streams which intersectat some angle to the stream being switched. Since the output signal isof a higher energy level than the input signal, the devices have beenreferred to in the art as fluid amplifiers. Such devices. are relativelyrugged and reliable, and occupy minimum space. Further, highly intricatefluid systems involving many basic devices may be constructed in alaminate arrangement at relatively low expense by stamping or otherwiseforming the layers or laminates from very thin sheet material, such asplastic or metal.

Pure fluid devices are characterized by the absence of moving parts.While they are not susceptible to inertial forces, the known deviceshave relatively high system output impedance. Further, pure fluiddevices often do not exhibit the necessary stability required in fluidcomputer apparatus.

In an effort to reduce system impedance and provide more stableoperation, pure fluid logic devices have been modified to include movingelements, such as globules of high density liquid metal, relativelymassive sliding members, rotating valves or ball valves. These modifiedfluid devices are highly subject to inertial forces due to the mass ofthe moving element. Further, close tolerance is needed between thelaminates forming the stacked array and the balls or like movable valvemembers.

It is, therefore, a primary object of this invention to provide animproved fluidic device which affords a high degree of fluid isolation,which requires a very small pressure differential to change the positionof the moving member, and in which the device exhibits high inertialrestraint.

It is a further object of this invention to provide an improved fluidamplifier which has very large flow gain with slight attenuation inpressure gain.

It is a further object of this invention to provide an improved fluidamplifier which requires very little flow from a driving Coanda element,thus permitting a large fan-out.

It is a further object of this invention to provide an "ice improvedfluidic device of this type which readily incorporates nondestructivememory means.

It is a further object of this invention to provide an improved fluidicdevice of this type in which the movable member may be moved as a resultof electrical impulse, or alternatively, as a result of fluid movement,the movable member indicates the extent of such movement electrically.

It is a further object of this invention to provide an improved binarycounter element which ensures high stability in each flow state.

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings.

In the drawings:

FIGURE 1A is an exploded perspective view of the improved fluidic deviceof the present invention in the form of an inverter-butter.

FIGURE 13 is a perspective view of the fluidic device shown in FIGURE 1Awith the pill moved to the other extreme position.

FIGURE 2A is a perspective view of the improved fluidic device of thepresent invention acting as a selective unidirectional element.

FIGURE 2B is a perspective view of the device shown in FIGURE 2A withthe pill in the opposite extreme position.

FIGURE 3 is a plan view of an improved double input, pressure selectiveoutput fluidic device of the present invention.

FIGURE 4A is a plan view of an improved bistable element using themovable pill of the present invention.

FIGURE 4B is a plan view of the device shown in FIGURE 4A with the pillin the opposite fluid position.

FIGURE 5A is a plan view of an improved diode of the present inventionemploying the movable pill with the pill in flow preventive position.

FIGURE 5B is a plan view of the device shown in FIGURE 5A with the pillin flow position.-

FIGURE 6 is a plan view of a multiple NO-R element using the principlesof the present invention, with the elements arranged in series.

FIGURE 6A is a plan view of a multiple NA-ND (negative coincidence)element, using the principles of the present invention, arranged inparallel.

FIGURE 7 is a plan view of an amplifier inverter with pressure and flowgain using the principles of the present invention.

FIGURE 8A is a plan view of a high gain inverterbuifer using theprinciples of the present invention,

FIGURE 8B is a plan view of the device shown in FIGURE 8A with thedifferent size pills in the extreme right-hand position.

FIGURE 9A is a plan view of a pulse amplifier utilizing the principlesof the present invention with the pills arranged in a first position.

FIGURE 9B is a plan view of the device shown in FIGURE 9A with the pillsmoved to a new extreme position as a result of pulse input.

FIGURES 10A, 10B, 10C and 10]) are schematic views of a simple binarycounter using the improved pill-type fluidic elements of the presentinvention, with the pills in various sequential positions.

FIGURE 11 is a schematic view of an up and down binary counter stageutilizing completely pill-type fluidic devices of the present invention.

FIGURE 12 is a schematic view of an up and down binary counter stageusing a combination of the pill-type fluidic devices of the presentinvention and conventional Coanda elements.

FIGURE 13 is a plan view of a basic (Coanda effect) bistable fluid logicelement including a single pill-type fluidic device in an input controlfunction.

FIGURE 14 is a plan view of a modified fluid amplifier in a modifiedform employing the pill-type fluidic device of the present invention.

FIGURE 15 is a schematic view of an up and down counter using apill-type fluidic device of the present invention.

FIGURE 16 is a plan view of a binary counter incorporating a hollow pillas a flow control element under the principles of the present invention.

FIGURE 17A is a plan view of an improved fluidic device of the presentinvention incorporating memory means for positively locating the pillwithin its fluid slot.

FIGURE 17B is a side elevation of the device shown in FIGURE 17A.

FIGURE 18 is an elevational view, in section, of a portion of the deviceshown in FIGURE 17B showing the locking effect of the magnetic field onthe ferromagnetic spring member.

FIGURE 19 is a plot of the hysteresis loops of the materials formingportions of the apparatus shown in FIG- URES 17A and 17B.

FIGURE 20 is a side elevation of yet another embodiment of the pill-typefluidic element having magnetic memory means.

FIGURE 21 is a side elevation, in section, of yet another embodiment ofthe present invention.

FIGURE 22 is a schematic view of a pulse flow amplifier forming anotherembodiment of the present invention.

Referring to the drawings, all of the elements, devices, amplifiers,counters and the like incorporate or comprise a fluidic device includingan enlarged fluid slot therewithin, which carries a member, movablebetween extreme fluid positions, to variably couple multiple fluidports.

The present invention is characterized by the presence of a low masspill, either in solid disc form, or as a hollow cylinder, which moves asa result of a small fluid pressure differential from one extremeposition to the other; and, as a result, offers considerable reductionin flow requirements and element-to-element impedance matching problemsas compared to conventional pure fluid devices involving the Coandaprinciple.

A typical pill element is shown in FIGURES 1A and 2A. This particularconfiguration serves as an inverterbuffer or inverter-flow amplifier. Asin typical fluid device construction, the device is formed principallyby stacking a series of laminates or layers, such as base 12,intermediate section 14 and the cover 16 to form a completely sealedfluidic device except for the port areas. The laminae may be formed fromsheets of plastic, metal or the like which may be mechanically milled,chemically treated or etched as desired to form the desired fluid logicpath. In this respect, the intermediate layer 14 is provided with port18 to which is directed the control pressure P A low impedance fluidicsource, at bias pressure P is applied to port 20. When the controlpressure P is reduced at 18 below P at 20, the pill 24 moves to the leftend of the slot allowing free passage of flow to the output port 22.Pill 24 which, in this case, is a solid disc of lightweight material,such as plastic, fits within an enlarged, elongated slot 26 havingrounded ends 28 and 29 respectively. Thus, in FIGURE 1A, P at outletport 22 equals P at inlet port 20. The diameter of pill 24 is slightlyless than the width of the elongated slot 26 and at the same time thereis no appreciable gap between the faces of the disc 24 and the contactsurfaces of either base 12 or cover 14. Thus, the close fit of the pillin the slot allows very little flow past the pill into the control port,thus affording a high degree. of isolation. When P at port 18 is raisedabove P at port 20, the pill moves to the right end of the slot, withinrecess 28, shutting off the flow and the output pressure P drops to verynearly the system vent pressure. Note that the pill provides the sameisolation of P from both the bias P and the system vent. Thischaracteristic allows a large fan-out wherein a large number of pillelements may be driven from a Coanda element with very little flow;hence, very little of the characteristic loss of gain that normallyresults when a Coanda element drives a significant flow load. While pill24 is shown in this embodiment, as well as all other applications exceptFIGURE 16, as being a solid disc, reduction in mass is readily availableby using a hollow disc. At the same time the pressure difference neededto move the disc from one extreme position to the other extreme positionis materially reduced. Further, by using a hollow disc or pill, thedevice is even less susceptible to inertial forces. As a result, anyfluid device which utilizes the pill-type fluidicelement could be usedin high speed aircraft or missile applications with maximum reliabilityand system stability.

The partially exploded, perspective view of FIGURE 1A discloses thesandwich concept or multiple lamina stack to achieve the desired,sealed, fluid logic device. The remaining figures either show inperspective, plan or schematic views other arrangements utilizing thebasic pill technique of the present invention without specificallydisclosing the lamina type of structure which is common to fluid devicesof this type. For instance, FIGURE 1B which shows the pill 24 in theextreme right-hand position as the result of P being greater than P isshown with the cover 16 eliminated. With the pill so arranged, the pill24 blocks any direct flow (except the very small leakage) from the inputport 20 to the output port 22 Where P is greater than P or flow from thebias port back through the input port when P is less than P The pill 24,being very light, requires only a very small pressure differential tomove it within slot 26. Hence, an input pressure P significantly greaterthan the bias pressure P results in a near zero pressure output P(signal inversion). Conversely, an input pressure significantly lessthan P results in P being equal to P FIGURE 1A.

Element 10 thus provides inversion with an output pressure gain ofgreater than 1 but with considerable flow gain (since the flow requiredinto the inlet port is only a small leakage past the pill), andconsiderable power gain. This characteristic is particularly useful inintegrating the logic element into computer circuits, since it does notload down the previous logic stage, yet provides a significant poweroutput to drive a number of parallel succeeding logic stages (fan-out).This element, therefore, forms a basic building block for some of theelements following.

Reference to FIGURE 22 shows a pulse flow amplifier which is, inreality, the inverter-flow amplifier or inverterbulfer of FIGURES 1A and1B with a fluid restriction in the biasing pressure line. The schematicteaching employs an elongated slot 926 receiving a solid or hollow pill924. The slot is fluid sealed with the exception of control port 2 atcontrol pressure level P and at the opposite end aligned, opposed ports904 and 906. Flow between ports 904 and 906 is blocked when pill 924 isin the extreme right-hand position. Port 906 acts as a vent port Whileport 904 is fluid coupled at 908 to biasing pressure line 912. A fluidrestriction 910 is provided between the coupling point 908 and a sourceof biasing pressure P The biasing pressure P passes through connection908 to outlet port 914 at pressure level P In operation, when thecontrol pressure P is equal to O, the output pressure P at port 914-approaches 0 due to venting of the biasing fluid line 912 by the shortcircuit through port 904 and vent port 906. Likewise, when controlpressure P is greater than biasing pressure P pill 924 is moved to flowblocking position insofar as vent port 906 is concerned. Therefore, theoutput pressure P at port 914 approaches the biasing pressure P FIGURES2A and 2B show a selective unidirectional element 30 which includes thesame general arrangement of elements; that is, three fluid ports and asingle elon gated slot containing the slidable pill 24 movable withinpill slot 26. The output pressure P at center port 32 is always the sameas the highest input pressure either P at port 34 or P at the oppositelyoriented port 36. The higher input pressure, such as P in FIGURE 2A, isprevented from rfeeding back into the lower input pressure port, such asport 34. Alternatively, in FIGURE 2B, output pressure P is equal toinput pressure P with pill '24 moved to the right end of slot 26blocking fluid connection to input port 36 which is at a lower pressureP The selective unidirectional element 30 is very useful for adaptingtwo alternate signals to a single input so that neither interferes withthe other. Likewise, element 30 forms a basic building block for theelements and systems to follow.

FIGURE 3 discloses a double input, pressure selective output device 40which again employs the single slot 26, the solid pill 24, and therounded slot ends 28 and 29 which ensure flow blockage when the pill isin contact position. The element 40 includes spaced fluid input ports 38and 42 and aligned output ports 44 and 46 respectively. In the positionshown in FIGURE 3, pressure P at port 38 is greater than the pressure Pat inlet port 42, and the pill is moved to the extreme right, causing Pto be at pressure P and output pressure P at port 46 to be approximatelywith slight fluid leakage. Obviously, if pressure P at inlet port 42becomes greater than the inlet pressure P at port 38, the pill 24 willmove from right to left allowing fluid communication between ports 42and 46, and the output pressure P at port 46 will be approximately thesame as inlet pressure P at port 42. Outlet pressure P at outlet port 44then drops to 0 as a result of the blocking of pill 24 as it is receivedby the recess or curved section 29 at the left end of slot 26.

The small arrows at the entrance, exit and vent ports throughout thespecification in relation to all figures indicate the flow direction forthe fluid depending upon the conditions within the respective element ordevice. Where no arrow is shown at a port, no flow is occurring ineither direction.

FIGURES 4A and 4B show a basic fluid bistable element 50 employing thepill-type fluid control device. The pill slot 26 in this case has fiveports, two at each end, 48, S2, 54 and 56 respectively and one in thecenter at 58. A bias pressure P is fed to center port 58. As shown inFIGURE 4A, the output pressure P at port 52 is equal to P The outputpressure P at port 56 is at a near 0 as the pill 24 is retained at theright end of the slot, since P at port 58 is greater than quiescentlevels of P and P at ports 48 and 54 respectively. To reverse theelement, P is increased significantly above P which moves the pill 24 tothe left end of slot 26. The pill will remain there when P is reduced toits quiescent level, and P at port 56 will be equal to P while P at port52 will be near 0 as shown in FIGURE 4B. The element may then berestored to its original state by increasing P above P thus moving thepill to the right. Optional unidirectional elements may be added aheadof the control ports to prevent the output pressures from tfeeding backinto the control lines when the control pulses are not being sent intothe element. The element as thus modified offers higher stability ineach flow state to variations at output loading than the typical Coandatype element, although it requires relatively higher control pressuresto change it from one state to the other.

FIGURES A and 5B show another pill-type fluidic element which becomes abasic building block in the fluid computer art. The device 60 comprisesa unidirectional element which performs a diode function in any fluidlogic system. Again, the basic device includes a pill receiving slot 26,the pill 24 with single ports 62 and 64 at either end. The third port 66which like the devices in FIGURES l and 2 is at the center of theelongated slot 26 is externally connectedto one end port, such as port64. When flow is applied from left to right, the pill 24 moves to aposition shown to the right end of the slot allowing passage of thefluid through conduit 68 from port 66 to port 64 through the by-passport 68. However, when flow is applied from right to left, the pill 24moves back past the center port and blocks flow through either theby-pass 6-8 or through the pill slot 26 as in FIGURE 5A. The by-passpath 68 should either be slightly longer, or have slightly greater flowresistance than the direct path 72 from the junction to the end port 64to be sure that the pill will move to the block flow position when theapplied flow is from right to left.

The negative alternate (NOR) element shown in FIG- URE 6 comprises twoor more inverter-buffer elements, such as those shown in FIGURES 1A and1B, whose bias and output ports are connected together in head-totailfashion. In this respect, the NOR has incorporated therewithin aplurality of pill receiving slots, such as slots 26A, 26B, 26C and 26D,all of which are series connected by a right angle fluid conduit orconnecting path 72. The fluid path 72 forms a pressureabiasing port 74at one end to which is applied the biasing pressure P and an output port76 at the other end which has output pressure P Each inverter-bufferelement in the order shown includes a control or input port 78, 82, 84and 86, respectively, to which is selectively applied input or controlpressures P P P and P1 The respective pill elements 24A, 24B, 24C and24D are positioned at respective ends of their slots depending upon theratio existing between the input pressures and the biasing pressure.With the biasing pressure P applied at the bias port at one end of thechain, the element output comes from the port 7 6 at the other end ofthe chain. In operation, the application of any one (or more) inputpressures P through P being less than the bias pressure P results in theoutput pressure P =P Inversely, if any one of the control pressures Pthrough P is greater than the biasing pressure P then the outputpressure P is equal to near 0 as indicated in FIGURE 6. In FIGURE 6, Pis greater than the biasing pressure P and P equals 0. With respect tothis particular device, a large number of inputs (fan-in) can beaccommodated, and because the inputs are not summedor added (as in theusual electronic equivalent), the allowable tolerances to avoidambiguity, required of the input levels, do not become successivelytighter with the increasing number of inputs, as in the case with theusual electronic equivalent circuit.

In FIGURE 6A, a negative coincidence (NAND) element 800 is provided.This fluidic element or device is similar to the NOR element shown inFIGURE 6, except that the output ports are connected to the biasingpressure inlet in parallel rather than in series. Again, multipleinverter-buffer elements 801, 803, 805 and 807 are provided within NANDelement 800. Biasing pressure P is delivered to the element throughinlet port 802 and outlet pressure P is provided at outlet port 812.Parallel inlets 804, 806, 808 and 810 are provided, respectively, forsections 801, 803, 805 and 807; and parallel outlets 820, 818, 816 and814 lead from respective NAND segments 801, 803, 805 and 807 to thecommon outlet port 812. Each of the NAND segments includes longitudinalpill slots 26 and the pills 24 and individual control pressures P P Pand P are delivered to respective NAND sections 801, 803, 805 and 807 bycontrol ports 822, 824, 826 and 828, respectively. In operation, P atport 812 will remain nearly equal to P at port 802 until all of thecontrol pressures P through P are increased above the biasing pressure PWhen this occurs, all of the pills move from left to right or flowblocking position and this drives the output pressure P to near 0. Hereagain, the tolerances on control pressures are wide compared to theequivalent electronic circuits employing signal-adding techniques.

Reference to FIGURE 7 shows a high gain inverterbuffer 80 which issimilar in operating principle to the inverter-bufier 10 shown inFIGURES 1A and 1B. In this case, however, two pills of different sizesare used, a relatively large diameter pill 24E and a relatively smalldiameter pill 24F. Instead of a single longitudinal slot, a largediameter lot 26E receive the large diameter pill 24E and merges into asmall diameter slot 26F. The input of control pressure P exists atcontrol port 18 and a biasing pressure P is delivered to the biasingport 20'. A variable output pressure P is presented at the outlet port22'. The pressure gain (the ratio of input pressure to shut oif outputpressure) varies with the ratio of pill diameters of radii (assumingboth pills are the same thickness). For the condition shown in FIGURE 7,the input pressure P is greater than the biasing pressure P times theratio of the radius R of the small pill over the radius R, of the largepill. (If pills of diiferent thickness are used, then P /P=cross-seetion area of large pill/cross-section of small pill.)

Preferably, a vent to atmosphere is provided between the pills. FIGURES8A and 8B show a modification to allow such venting. In this embodiment,the vent ports 88 are presented centrally of the device, at the point ofmergence between the small diameter slots 26B and 26F. The high gaininverter-buffer 90 in this embodiment is shown in FIGURE 8A underconditions in which the control pressure P is less than the biasingpressure times the ratio of the small pill radius R over the large pillradius R Again, the assumption is made that the pills are of equalthickness. In this case, the output pressure P at port 22' is equal tothe biasing pressure P This is contrasted to the conditions of thedevice as shown in FIG- URE 8B which is similar to the position of theelement shown in FIGURE 7 in that the control pressure P is greater thanthe biasing pressure P times the ratio of the small diameter radius R ofthe small pill 24F over the radius R of the large pill 24E. In thiscase, P is equal to near 0.

Two of these elements, in tandem, may form a pulse amplifier with alarge flow and power gain and a pressure gain approximately equivalentto the product of the element gains. Such a pulse amplifier 100 is shownin FIG- URES 9A and 9B. Note, however, in this case the two levels ofbias pressure required. Referring to these figures, it is seen that thepulse amplifier 100 includes an input or control pressure port 102, acommon vent port 104, an output pressure port 106, a biasing pressureport 108 at pressure P vent ports 110 and 114 and biasing pressure port112 biasing at pressure P Under the conditions shown in FIGURE 9A, theoutput pressure P is 0 when the input or control pressure P is less thanbiasing pressure P at port 108 times the pill radii quantity and biasingpressure P is equal to the biasing pressure P at port 112 times theratio of pill radii R /R (assuming all pills have the same thickness).Under such conditions, the biasing pressure P maintains the pills 24Gand 24H to the extreme left position in respective slots and the biasingpressure P maintains pills 241 and 24] in their extreme left-handpositions within respective slots to close off the connections betweenthe biasing pressure P port 108, and the outlet port 106. The outletpressure P then is approximately 0. However, referring to FIG- URE 9B,when the control pressure P becomes greater than the biasing pressure Ptimes the quantity RzX R4) R R and is equal to biasing pressure P timesthe ratio of pill radii R /R a shift in pill position occurs in whichthe pills move from left to right in their respective slots. The outletpressure P at port 106 now becomes equal to the biasing pressure Pappearing at port 108.

A binary counter element is derived from a modification of the bistableelement shown in FIGURES 4A and 4B and may be made by the addition ofthe several simple building block elements previously described, asshown in FIGURES 10A through 10D inclusive. It should be noted that thecounters shown in the drawings and described herein are capable ofcounting to two, but in actual practice, a plurality of count to twocounters, otherwise called stages, form counters capable of counting upto any desired value depending upon the numbers of stages. In likemanner to the FIGURES 4A and 4B embodiment, the basic bistable elementindicated at 50' includes a sliding pill 24 moving within slot 26,selective output ports 116 and 118, a common biasing port 120 and inletcontrol ports 122 and 124, respectively. Diode 60' is connected to eachcontrol port 124. Diode 60" is connected within bistable biasing portinlet 120'. The inlet lines 122 and 124 are coupled selectively to pulsereceiving inlet line 130 through a pill-type shuttle valve 30'. Shuttlevalve 30' comprises a selective unidirectional element, such as 24, inFIGURE 2A. A diode 60" is connected in series between the pulse input130 and shuttle valve 30. A pair of feedback loops 126 and 18,respectively, are coupled to the control lines 124 and 122 intermediateof the shuttle valve 132. The feedback loops also include diodes 60".The feedback loops 126 and 128 are cross-connected to outlet ports 116and 118 respectively. Of course, each of the fiuidic elements formingthe simple binary counter include the sliding pills 24 within respectiveslots 26 and operate in this combination in the exact manner describedpreviously when the devices were treated as separate elements. In thisrespect, referring to FIGURE 10A, and assuming momentarily thatconditions are such that the control pressure P at pulse inlet 130 isequal to zero, the pressure P at outlet port 116 is equal to the biasingpressure P at biasing port 120 of the bistable element 50 (the biaspressure diode 60" being in the flow position), since its pill 24 is atthe extreme righthand position then output pressure P at outlet 118 isnear 0, as the pill 24 prevents fluid connection between the biasingpressure and the outlet port 118.

Moving to FIGURE 10B, inlet pressure P momentarily, as a result of apulse input, becomes greater than the biasing pressure P which sets thebias pressure diode 60" to the no flow position. This also moves pill 24of diode 60" from its blocking position to the unblocking position shownto allow the fluid pulse to pass to the shuttle valve 30'. The pill 24of shuttle valve 30' remains in the extreme left-hand position and thehigh pressure fluid passes into control line 124 through its respectilvediode 60 to the bistable element 50'. Since the control pulse P isgreater than the biasing pressure P the pill 24 in the bistable deviceis moved from its extreme right-hand position to its extreme left-handposition allowing fluid connection between pulse inlet port 130 atpressure level P and the outlet port 118 at pressure level P Theleft-hand-outlet port 116 has its pressure P reduced to 0, since thepill 24 of bistable element 50 is moved to the extreme left-handposition within its slot. In feedback path 128 associated with outletport 118, the relatively high increase in pressure which is somewherenear P has moved the pill 24 of its diode 60" to unblocking position inwhich case the feedback pressure is being exerted on the left-hand faceof pill 24 within the shuttle valve 30.

FIGURE shows the position of the elements within the binary counter as aresult of removal of the inlet or control pulse P at port 130. With thecontrol pressure P zero at port 130, the pill of diode 60" moves to flowblocking position. Insofar as the bistable element 50 is concerned, thebiasing pressure P applied at central port (the bias pressure diodemoves again to the flow position) maintains its pill 24 in the extremeleft-hand position and the output pressure P at outlet port 118 nowbecomes equal to the biasing pressure P while the output pressure P atthe outlet port 116 remains at 0. The feedback path 128 maintains pill24 of its respective diode 60' in the flow blocking position allowingthe pressure P to be applied to the pill 24 of shuttle valve 30 whichmoves the pill from the extreme left-hand position to theextremeright-hand position, and also unblocks pill 24 of the diode 60".The same feedback path further maintains pill 24 of the diode 60' of thebistable inlet 122 in the flow blocking position. Pill 24 of diode 60"in feed back loop 126 is in the intermediate position since it issubjected to zero pressure on both sides.

FIGURE 10D shows the position of the elements as a result of the simplebinary counter receiving the next pulse count at receiving inlet port130. P again becomes greater than P unblocking the diode 60" and closesthe bias pressure diode. This allows the high pressure pulse P to travelto shuttle valve 30. Since the pill 24 of shuttle valve 132 is in theextreme right-hand position, the high pressure fluid P passes by way ofbistable element input 122 through its diode 60 to the bistable elementitself. This has the effect of moving its pill 24 from the extremelefthand position to the extreme right-hand position causing the outletpressure P at outlet 116 to move from to P Movement of the pill 24 fromthe extreme left-hand position to the extreme right-hand position of thebistable device causes theoutlet pressure P in outlet port 118 to dropto 0. With respect to the feedback loops, in feedback loop 126 which issubjected to pressure P the pill 24 of its diode 60" moves from theintermediate to flow unblocking position unblocking diode 60 associatedwith bistable inlet 124. Further, since the pressure P in outlet 118 isdropped to 0, pill 24 of diode 60" and feedback loop 128 move into flowblocking position as a result of the high pressure P being applieddirectly to this diode through shuttle valve 30'.

Briefly, in summary, FIGURE A shows the initial setting of the elementpills in the binary counter prior to application of the first inputpulse to the counter. Upon the application of a count pulse P thebistable element is reversed as indicated in FIGURE 10B. FIGURE 10Cshows the shuttle valve pill reversing upon removal of the count pulse Pand FIGURE 10B shows the bistable element resetting to its original sideupon the second count pulse; when the second count pulse is removed, theshuttle valve resets and the element reverts to the condition shown inFIGURE 10A. A full two pulse count cycle has been completed.

Referring to FIGURE 11, there is shown one arrangement for a reversiblecounter (up and down). Again, this system uses only pill elementsconsisting of the simple binary counter 50" of the type shown in FIGURES10A through 10D, two three-input (NAND) elements 151 and 153 of the typeshown in FIGURE 6A, hereinafter simply referred to as NANDs and two highgain inverter-buffer elements 167' and 169' of the type shown in FIGURE7. This counter arrangement offers excellent stability, ease ofadjustment, output power gain and minimum operating air flow.

Since the operation of the simple counter shown in FIGURES 10A through10D inclusive has been described in detail and since the operation ofthe simple counter 148 shown within the dotted line section of FIGURE 11is identical, a detailed description of the elements and their specificmode of operation is not included here. Suflice to say that inlet port130 periodically receives pulse counts in the same manner as the counterpreviously described and that the counter 148 will alternately deliverpulses to outlet lines 116 and 118, respectively, in response to pulseinput. A further modification is made in that a pair of branch inletlines 150 and 152 deliver pulses simultaneously to segment or component156 of NAND 151 and component 162 of NAND 153. Further the outlet pulsesfrom outlet ports 116' and 118 pass to components 158 and 164 of NANDs151 and 153, respectively. As mentioned previously, the device operatesas an updown" binary counter stage and in this respect, up signal Pxpasses through lines 176 to segment 154 of NAND 151 and the down signalPdown is delivered through line 178 to segment 160 of NAND 151. A secondcontrol pressure P is delivered by means of port 166 to NAND 151 and thesame biasing pressure P is delivered to port 168 of NAND 153. The outputports 167 and 169 are attached as the input ports to inverters 167 and169 whose output ports are in turn connected together to provide outputpulses at P02 for every other input pulse of flow pressure at PC1-Periodic pulse counts are delivered at port wherein the pressure risesfrom 0 to P This results in changing outlet pressures at ports 116' to118 subject to continuous biasing pressure P with the pressures beingalternately delivered to NAND segments 151 and 153 in the alternatefashion mentioned previously. Of course, the pressure P which is actingupon one side of the NAND segments 158 and 164, respectively, is opposedb the biasing pressure P which attempts to pass from inlet ports 166 and168 to the respective outlet ports 167 and 169 in typical NAND fashion.Since the biasing pressure P is greater than the biasing pressure P thepill for NAND segment 164 will move to flow blocking position as shown,while the pill associated with NAND segment 158 will move to unblockingposition due to the pressure differential.

Further, as a result of pulse count delivery to the inlet port 130,fluid pulses will travel through conduits and 152 to the NAND segments156 and 162. Since the pressure at the control or inlet port 130 risesfrom 0 to a value equal to biasing pressure P which is greater thanbiasing pressure P the pill associated with NAND segment 162 moves fromleft to right in response to pulse count input at 130 andsimultaneously, the pill associated with NAND segment 156 will move intoflow blocking position. The up and down mode is determined by theselective delivery of an up or down fluid signal pressure, P and Pdownat inlets 176 and 178 connected to NAND segments 154 and 160,respectively.

Referring to FIGURE 12, there is shown a modified, reversible (up anddown) counter stage which combines pill and Coanda type fluidicelements. The arrangement of FIGURE 12 is essentially identical with thearrangement of FIGURE 11 with the exception that the bistable device 148of FIGURE 11 is replaced by a Coanda bistable element of conventionalconfiguration, as indicated by the dotted line section 200, and a pairof Coanda pulse amplifiers indicated by dotted line sections 950 and 952between NANDs 204 and 206, respectively, and the pulse counter outputfor the next stage. In addition, a pulse flow amplifier 954 of the typeshown in FIGURE 22 is positioned between the common Coanda pulseamplifier outlet and the counter stage outlet 220. The Coanda bistableelement 200 includes a power stream at pressure level P emanating fromentry port 202. The parallel NANDs 204 and 206 are identical in functionto NANDs 151 and 153 of the FIGURE 11 embodiment. The high gaininverter-buffer 80" forming a portion of the system of FIGURE 11 isreplaced by the two Coanda pulse amplifiers indicated by dotted sections950 and 952 which also receive a power stream at pressure level Pthrough ports 210 and 210", respectively. Each Coanda type pulseamplifier is connected to its respective NAND. For instance, NAND 204 iscoupled to Coanda amplifier 950 by means of common NAND outlet 228 whichacts as a control port source for the pure fluid Coanda type pulseamplifier 950. With respect to Coanda 950, one outlet line 212 isconnected to the flow pulse amplifier 954 which, when activated, removesa flow short circuit. Thus, this action selectively completes a fluidconnection between a second biasing port 218 at pressure level P andport 220 delivering the output count pulse P Since Coanda elementsreplace the pill-type fluidic devices, various flow restrictions 222 areprovided in the multiple fluid paths. The fluid pulse count outletpressure P varies from to pressure level P depending upon the positionof the pill within the flow amplifier 954. The second Coanda type pulseamplifier 952 includes identical elements and connections to the Coandaamplifier 950 and identical numerical designations have been providedwith the addition of prime mar-ks. Under fluid pressure conditions asshown, the power stream P emanating from inlet port 202 passes fromCoanda element 200 through line 224 to NAND section 206. The inlet pulsecontrol pressure P is 0 as no count pulse is being received. Thereversible counter is in the down mode and the biasing pressure P passesthrough the NAND section 204 to common outlet 228 and acts as a controlpulse to the Coanda amplifier 950. This control pulse is opposed atcontrol port 230 which is open to the atmosphere at P The power stream Pemanating from inlet port 210 for the Coanda amplifier 950 passes outthrough the vent line 216. With no flow in either line 212 or 212'associated with Coanda pulse amplifier 952, the pill associated with thepulse flow amplifier 954 remains in the left-hand position as shownmaintaining flow connection between biasing pressure P inlet port 21-8and vent port 238. The counter output signal P at outlet port 220 istherefore near 0. During the next portion of the cycle, the position ofthe pills within NANDs 204 and 206 drop the pressure at control ports228 and 228' of the respective Coanda elements to 0 causing the powerstreams emanating from ports 210 and 210 to flip from outlets 216 and 216' to outlets 212 and 212'. Fluid is then delivered at pressure level Pthrough opening 210, line 212, common lines 232 and 234 to the flowamplifier 954 causing the pill to move from left to right to flowblocking position, thus cutting off the flow short circuit through theport 238 and its vent, whereupon the pressure P at port 220 rises againto pressure level P due to the absence of the direct venting path.Obviously, reversing the mode from down to up results in blocking port218 displaced 180 in the cycle from that shown under the conditionsindicated in FIGURE 12. 'In the system shown, port 236, in conjunctionwith its flow restrictor 222, provides a vent in the pulse amplifierdelivery path including lines 232 and 234 to the flow amplifier 954.Upon movement of the respective Coanda pulse amplifier out-puts intovent paths 216 or 216', the fluid pressure is relieved in lines 212 and212' through the vent port 236'.

The reversible counters in FIGURES 11 and 12 are in schematic form. Inorder to fully understand the operation of a combined Coanda andpill-type fluidic device, reference to FIGURE 13 shows a plan view of afluid bistable element 250 which is similar to the element shown in thelower portion of FIGURE 12. The Coanda element is typical of suchdevices in that it has the standard Coanda configuration involving ateardrop shaped power stream inlet port 252 to which is delivered thepower stream at pressure P which flows out through the narrow neck 254towards baflle 256 at the rear of a V-shaped chamber 258. The pure fluiddevice incorporates on both sides of the V-shaped chamber side walls 260and 262, respectively, which, along with somewhat parallel walls 264 and266' respectively, provide output legs or paths receiving the powerstream depending upon which of the control ports 268 and 270 has lastbeen pulsed. As in conventional Coanda fashion, the power streamindicated by the dotted arrow 272 tends to hug either the left wall 260or the right wall 262 and maintains flow in this manner even after thecontrol stream pulse ceases in either control port 268 or 270. Thedevice is further characterized by a count pulse inlet at 274, apill-type selective output element 275, and selective outlets 276 and278. Fluid paths 276 and 278 are connected to control ports 268 and 270,respectively, at the point of mergence with feedback loops 280 and 282.The Coanda outlet 290 terminates in a vent port 284 while Coanda outlet292 has coupled to it, a vent port or tube 286, and a second outlet port288 which delivers the count pulse to the next stage. Suitable flowrestrictors 294, 296, 298, 300, 302 and 304 are provided in all lines toprovide the required flow impedance therein. In the position shown, theinitial memory state of the bistable element 250 is such that the mainpower jet 272 flows into the left leg of the Coanda element at 290. Mostof the flow passes through the flow restrictor 294 associated with port284 and is vented to the atmosphere. A small part of the jet flowbecomes a feedback flow through line 280 including its flow restrictor.Thus, P in let 290 is greater than P in leg 292, and the pill 24 isretained at the right end of the slot since the pressure P is greater onthe left-hand side in fluid passage 276 than pressure P in right-handpassage 278. Thus, even after the pulse count ceases in line 274, thepill 24 remains in the full line position shown. Note that while thepressure P is less than the pressure P due to the effect of the inducedfeedback flow through flow restrictor 296 and into the left control port268, P will remain close to 0 or atmospheric pressure, since pressure Premains at nearly 0 pressure relative to the atmosphere and the rightcontrol port induces little or no feedback flow. When a count pulse isreceived from a previous stage or sensor within port 274 as indicated bythe arrow, flow passes through the pill valve selective output element275 directly into the left control port 276 while the pill 24 blocksflow into the right-hand control port 278. The count pulse pressure mustbe somewhat greater than P to change the flow state (flip) of thebistable element 250. When the bistable element flips, the main powerjet at 272 moves from the left leg 290 into the right leg 292. Most ofthe flow passes through flow restrictor 304 and is vented to atmospherethrough port 286. A small part of the flow becomes a feedback flowthrough feedback loop 282 and restrictor 302, while the remainder formsa count pulse signal which passes through port 288 to the succeedingcounter stage. The pill 24 will remain at the right end of its slot aslong as the count pulse is held, since the count pulse pressure isgreater than the pressure P existing within right-hand control port 276..When the count pulse is released and there is no flow in port 274 (itspressure drops close to atmospheric), then pill 24 will move from theright-hand slot to the left-hand or dotted line position, since thepressure P is greater than the pressure P Thus, the conditions of theelement prior to the arrival of the count pulse are re-established butin reverse with respect to the sides of the element. The next pulsereceived by port 274 will flip the main power jet 272 back to the leftand upon its release, the pill will be moved to the right side of theslot, as shown in FIGURE 13. Flow restrictors 298 and 300 are optionaldepending upon the bistable elements control port characteristic; thegreater the negative pressure induced on the flow side, the greater theflow restriction required.

FIGURE 14 shows an alternate pneumatic circuit arrangement, in planview, in which a negative pressure generated by flow in the output legusing a Venturi tube arrangement moves the pill after the removal of thecount pulse. This arrangement is more useful when the device is operatedmore nearly as a flow amplifier rather than a pressure amplifier. Theutilization of the pill valve or selective output element 275' isidentical with that in the FIGURE 13 embodiment. The principaldifference here is that the left-hand feedback loop 280' instead ofbeing connected to the left-hand control port is connected to theright-hand control port 276', thus providing a negative feedback loopfor control port 270. Likewise, the feedback loop 282 is connected tocontrol port 268' in conjunction with left-hand control port 276'. Asshown, the less than atmospheric pressure at P causes the pill 24 tomove to the right-hand side since it is with pressure P which is atatmospheric pressure after arrival of the count pulse P and further, dueto the feedback connection 282' which is at atmospheric or nearatmospher-ic pressure P In the cyclic position shown in FIG- URE 14, nocount pulse is delivered to the next stage and P93 IS 0.

- Of course, the application IOf the pill-type fluidic device tocounters using Coanda type elements is not limited to the basic countersshown in FIGURES l3 and 14. For instance, FIGURE 15 shows a reversibleup and down counter 400 which, in fact, incorporates a pill valve binarycounter therein. The up and down counter 400 incorporates the binarycounter 401 therein which makes use of a unidirectional selectiveelement 408 to selectively deliver the power stream at pressure Pthrough outlet ports 410 and 412 to Coanda elements 432 and 434,respectively. The up-down counter includes Coanda type AND sections 436and 438. AND element 436 requires pill valve flow, such as the powerstream through outlet 410, a count-up signal at inlet port 414 and acOunt pulse from the previous stage P through inlet port 404 to flip thepower stream. In this respect, the ports 404 and 414 act as controlports for the Coanda element 432 against the vent bias of port 418 toeffectively flip the pressure stream passing through Coanda 432 fromvent leg 416 to leg 420 providing a count pulse output through commonport 430, as indicated at P If the device is operating in the down mode,the pulse P is delivered at outlet port 430 only when the Pdown signalis provided at port 428, a count pulse is received from the control port406 of the Coanda element 434 and pill valve flow occurs through counteroutlet 412; and this acts in opposition to the bias of vent 422 andflips the Coanda power stream from the right-hand vent leg 426 to theleft-hand leg 424. In this respect, a count pulse is provided only whenthe bistable device 401 flips in the proper direction as determined byeither by a count down" signal or a count up signal.

The pill-type binary counter 500 shown in the plan view of FIGURE 16' isagain a slight modification of the basic binary counter but in thiscase, makes use of hollow pills 502 and 504, respectively, to provide asystem which is extremely stable in operation, shows maximum inertialrestraint and in which an extremely small pressure differential may movethe pills between their extreme perative positions. The mass of the pillis greatly reduced. The pills may be formed by cutting a long, hollowcylindrical member, such as a tube of plastic material into segments ofdesired thickness. The counter 500 itself includes a pulse input port506 wherein the supply pressure emanating from port 512 passes intoeither the right or left-hand leg of the Coanda element 505 for deliveryto the 1" output port 508 or the "0 output port 510. The device isequipped with suitable feedback loops to move the pill 502 to alternateright and left extreme positions and also incorporate vents 522 and 524.The inverterbuffer segment 516 acts to selectively prevent passage offluid from pressure source 514 to vent port 520, thereby delivering thepulse output to the next stage at port 518 when the hollow pill 504 isin the extreme right-hand or flow blocking position. Of course, theflip-flop output pressure of Coanda element 505 must be greater than thepulse output to the next stage or pill 504 would remain in the left-handposition as shown.

The presence of the pills in the fluidic devices of the presentinvention makes immediately available several techniques for providinglong term or short-term memory, either with or without the applicationof fluid power during the memory period. The basis of these techniquesis to employ a permanent magnetic material (barium ferrite or the like)to form the pills or to form a portion of the pills, such as an insertwithin the hollow type pill of the type shown in the embodiment ofFIGURE 16.

The first of two different approaches to incorporate magnetic fluidmemory to the pill-like elements or devices is shown in FIGURES 17A, 17Band 18. This technique utilizes small diaphragms of ferromagneticmaterial which are kept remote from the plane of motion of themagnetized pills at all times where the operating pressure is applied tothe power channel of the fluidic devices in question, but which areforced close to the plane immediately upon removal of such pressure.This allows the magnetized pill to induce an opposite pole in theferromagnetic material opposed to it. The resulting mechanical forcethus produced will clamp the pill in its then present position. Thestage of a register or other multistable device may be thus preservedindefinitely even in very adverse environments, such as those subjectedto high acceleration forces until the reapplication of fluid power.Strong external magnetic fields will not affect the memory. Indeed, theonly kind of physical effect which could produce loss of memory would bethe heating of the magnetized pills above the Curie point which isapproximately 860 F. for the material used. Since this is outside theoperating range of most foreseeable applications, the magnetizedpill-type of memory offers obvious advantages.

One possible construction is shown in FIGURES l7 and 18 for a selectiveunidirectional element 600 which incorporates a 1 output port at 602 atthe left-hand end of slot 610; and a "0 output port 604 at the righthandend of the slot. Intermediate of the ends of the slot is the memory biaspressure port 606, and of course, the device incorporates a pill 608which is readily movable between the extreme ends. The device as so fardescribed appears to be identical to the fluidic device shown in FIGURES2A and 2B and operates in the identical fashion. However, referring toFIGURE 1713, it is noted that the laminated array or assembly includes abase member 612 of some thickness formed of non-magnetic material whichhas its inner surface 613 shaped so as to form a cavity 615. A singlefull lamina 616 extends throughout the element between the base 612 andthe laminae sections 614 which form the interior of the sandwich toprovide the elongated slot 610 receiving movable pill element 608. Acover plate 618 completes the sandwich. The cavity 615 has positionedtherein a small ferromagnetic spring leaf member 620 which rests againstthe bottom lamina. However, with fluid pressure applied during normaloperation of the fluid device, as indicated by arrow 624, to the extremeleft of cavity 615, the ferromagnetic spring leaf member is pushed ormoved away from the single full lamina 616 against the inner surface 613of the 'base member 612, as indicated by the dotted line position. In somoving, the spring leaf is driven against the exit port 622, thusclosing it. The magnetized pill 608 is moved from the extreme left-handposition within slot 610 as shown to the right-hand position when thefluid inlet to port 602 is greater than the fluid pressure at 0 outputport 604, whereupon the pill 608 moves from left to right allowingcontinued fluid communication between ports 606 and 602.

Referring to FIGURE 18, the magnetic field relationship between themagnetic pill 608 and the ferromagnetic spring leaf 620 is shown.Typical dimensions of the magnetic pill 608 are such that the diameteris equal to 0.1 centimeter and the mean length and the width of the pillL is equal to 0.1 centimeter and for a pill formed of nonoriented bariumferrite, B=1025 gausses, and H: 410 oersteds or alternatively, if agrain oriented material is used, the value for B is 2700 gausses and thevalue of H is 1030 oersteds. The single full lamina 616 comprises brass.005 inch in thickness and the ferromagnetic spring leaf 620 is formedof relay type silicon steel having small hysteresis and remanence of.005 inch thickness with .002 inch air gap at the time that there is nosupply pressure as at 624 with the strip position. As indicated inFIGURE 17B, the following situation is experienced. Virtually the totalflux emanating from one end of the pill will travel transversely in thesteel strip 620. Assuming the external permanence is only slightlyreduced by the presence of the steel (conservative), the flux density inthe steel at the 1 critical section, FIGURE 18, for non-oriented pills,B 2050 gausses, for oriented pills, B =5410 gausses. This is far belowsaturation. Taking the equivalent pole strength of the induced pole atthe surface of the steel as equal to the pole strength of the pillsurface, the clamping force is, then,

lbs.

where B is in kilogausses.

For non-oriented pills,

The pill weighs .00306 lbs.

X .040 .00000634 lbs.

Taking the friction coefficient of the pill on brass (static) as .3, thepill can withstand The displacement of the steel piece by the appearanceof pressure through about that is, the gap dimension of cavities 615,will remove virtually all of this force. It may be desirable in somecases to install a fixed pole piece permanently from the opposite end tobalance the small residual restraint.

All ferromagnetic materials exhibit more or less hysteresis. This is theterm applied to the phenomenon associated with the work done in changingthe flux density or direction in ferromagnetic material from one stateto another. The characteristics of various materials are extremelyvaried in this regard. Reference to FIGURE 19 shows a plot of thehysteresis loops as applied to various materials. For instance, theareas enclosed within the hysteresis loops are proportional to the workdone in reversing a magnetic state and then returning it to its originalstate. In transformer or other A.C. applications, it desirable to keepthis area small so as to avoid heating and waste of energy. In permanentmagnet materials, a large fat loop is desirable, for the material isused to store energy, and works in the second quadrant entirely.Specialty materials, such as Supermendur, develop very large values offlux density at very small applied field strengths, so that, even thoughthe hysteresis loop is rather narrow appreciable energy is stored in iteven with small applied fields. Such materials are quite expensive toproduce and must be protected from mechanical strain after the annealingprocess to preserve these characteristics. However, in providing memoryfor the pill-type multistable devices, they find excellent applicationsince the mechanical forces available from small induced fields in suchmaterials can provide considerable restraint of motion of the pills, yetbe kept small enough that the fluid driving forces can reliablyoverpower this restraint. The hysteresis loop for transformer steels isshown at 652, the hysteresis loop for typical permanent magneticmaterial is shown at 654, while the hysteresis loop for the material,such as Supermendur, is shown at 650. The dotted line 656 represents thevirgin curve. In using the hysteresis characteristics of the Supermendurmaterial to provide the magnetic memory function, the embodiment shownin FIGURE 20 is similar in some respects to the embodiment shown inFIGURES 17A through 18, except that small sheets of material having aproper hysteresis loop are permanently installed at about .40 inchdistance, for instance, from each side of the pill to be controlled witha pill of dimensions shown in FIGURE 18, for instance. Thus, the stackedarray 700 would include a base member 702, a cover 704 and anintermediate section 706 formed by a number of relatively thin shimsheets 708 non-magnetic material (brass, plastic, etc.) which arephotoetched, for instance, to form the desired geometry and stackedtogether to provide the extremely close tolerances desired. The slot710, in like manner to all previous embodiments, receives the pill 712formed of permanent magnet material, such as barium ferrite, or of analloy including barium ferrite, such as in magnetic powder form which ispermanently magnetized to provide the magnetic fields 714. Embeddedwithin the base 702 and the 704 adjacent the slot 710 are the thinsheets 716 of material having a proper hysteresis loop, such asSupermendur. With the sheets 716 installed at equal distances from thepill, the attractive forces would be very nearly in balance. In orderfor the pill to move, then it must do Work on the sheets to reverse thefield in some of the material and change the value of flux in otherparts. The force necessary to do this small amount of work must beapplied by the driving force on the pill itself. Obviously, a smallfluid pressure differential on opposite sides of the pill will move itfrom the extreme left-hand position to the extreme right-hand positionand vice versa. These forces will be greatest using a permanent magnetmaterial, for the embedded sheet 716, but the stiffness of the restraintwould be greatest using Supermendur. Different requirements obviouslywould result in the use of difierent materials. A moderately severemechanical environment would suggest the use of Cunife, acoppernickel-iron alloy which has large hysteresis at low inductance.The requirement for very high cyclic rate or clock rate in a register orother device which would require a memory means, would suggest the useof Supermendur or like material because of the great stilfness"available with small applied field strength. Typically, at 1500 gauss,Vicalloy has a hysteresis energy of about li joule per cubic inch ofmaterial, at 500 gauss, about .07 joule per cubic inch (10 ergs and 2 10ergs per cubic inch). In this case, about .00015 in. of material wouldbe involved per pill at any instant, so that at the higher flux densitynoted, dyne-cm. of work is required in moving a pill 1 cm. or 1.5dyne-cm. to move it 0.1 cm. (a force of 150 dynes). With the pillweighing about .00000634 lbs. which is equal to .00288 grams, thus at 1g. it exerts a force of .00299 980=2.82 dynes. Under such circumstances,the Vicalloy plates about .03" thick would provide memory restraint ofup to with no more than .01 cm. displacement. Using Supermendur, goodrestraint against several gs would be feasible with small driving forcesat very high rates.

In using a pill which is formed of a permanent magnet material or of analloy including permanent material which is magnetized in the order ofpill 608 and pill 712 of the previous embodiments, the movement of thepill between extreme slot positions may, as a result of this movement,provide an electrical indication of the position occupied by the pill orits previous direction of movement; or alternatively, the electricalmeans may be used to actually drive the pill to a new position withinthe slot and thus, vary the fluid path by electric-to-fluidic conversionmeans. For instance, referring to FIGURE 21, the addition of coils 750and 752 near the ends of pill slot 754 allows the coils to be usedeither for positioning the pill 756 electromagnetically, or detectingpill movement from induced voltages as a result of movement of apermanent magnet pill 756 relative to the stationary coils. In thearrangement shown, coil 750 is connected directly to a sensitive meter758 while coil 752 is connected directly to meter 760. Movement of thepill 756 from its extreme left-hand position as shown to the right-handposition will result 17 in inducing a signal first across meter 758 asthe pill moves away from coil 750 and sequentially a like inducement ofelectrical current through meter 760 as the pill moves underneath coil752, Obviously, with the pill 756 in the position shown, the applicationof electrical energy through coil 750 from an outside source (not shown)would result in the formation of a permanent magnet field in oppositionto the field 762 existing within the; permannent magnet pill 756, whichwould tend to drive the pill from the extreme left-hand position to theright-hand posi tion of the slot 754. The subsequent application of alike direct current through coil 752 would result in return movement ofthe pill to theposition shown in FIGURE 21. Such movement could besensed by the coil not acting as :a driving means and which has remainedconnected to the meter or other indicating device. In the most simpleform, the pill 756 may comprise a magnetic material which is notpermanently magnetized and, therefore, has no field of its own but ismerely subjected to a magnetic field emanating 'as a result ofcurrent'passing through either coil 750 or coil 752 to thereby move to aposition 754 centrally of the coil beingenergized at the particularmoment. For instance, if the pill 756 were formed of magnetic materialand an alternating current source or direct current source wereconnected :across coil 752, the resultant magnetic field would act uponthe magnetic pill and tend to move it to a position centrally withinslot 754 of minimum magnetic field energy. In this manner, simplifiedelectric-to-fluid conversion is provided. LWith the straightforwardarrangement shown, the fluidic control systems achieve immediatecompatibility with a wide variety of electrical sensors useful in spacecraft control systems. In addition to the induction sensor shown,coupling of fluidic circuits to such typical electrical sensors, assolar cells, IR detectors, RF antennas, etc., is envisioned.

The dimensions of the slot pill, pill materials, port dimensions andconfigurations are not critical'with the exception that the slots arepreferably rounded at the point of intersection with transverse fluidconduits or ports to ensure proper sealing when the pill is in the flowblocking position and that further, the diameter of the slot is greaterthan the width of the coaligned fluid ports so as to ensure propersealing in an axial direction. It is, of course, preferable to keep thesize of the slots and, therefore, the pills relatively small so as toincrease inertial. restraint and provide maximum stability for thefluidic devices employing the pill type moving element. In addition to adecrease in mass for the hollow pill device, such as that shown in theFIGURE 16 embodiment, reducing the pressure differential required tophysically move the pill between extreme fluid positions within theslot, the hollow disc-like; pill provides some resilience, whereupon thegreater "the pressure differential, the greater the sealing effectas'the pill is slightly distorted within the slot. This, of course, maybe or may not be an advantage depending upon the specific application.

While the invention has been particularly shown and described withreference to preferred embodiments there of, it will be understood bythose skilled in the art that the foregoing and other changes in formand details may be made therein without departing from the spirit andscope of the invention.

What is claimed is:

1. An improved pill-type fluidic counter comprising:

a bistable fluidic device including a power stream input,

first and second outlets to receive said power stream, thus defining thetwo bistable states, and two control ports for applying fluidic controlsignals to control the position of the power stream in said outlets;

a pill-type unidirectional selective element including a central inletand outlets at respective ends; pulse inlet means connected to saidcentral inlet of said unidirectional selective element; I meansconnecting said unidirectional element outlets to said bistable devicecontrol ports; and

feedback means connecting said bistable fluidic device outlets to saidunidirectional selective element outlets.

2. An improved pill-type fluidic counter comprising: fluid count pulseinlet means, a pill-type bistable element including a biasing pressureinlet, a pair of control pressure inletsland spaced outlets coupledrespectively to opposite ends of said bistable element slot, a pill-typeunidirectional selective element including a central inlet and outletsat respective ends, means connecting said inlet pulse means to saidunidirectional selective element, means connecting said outlet ports ofsaid unidirectional selective element to respective control ports ofsaid bistable element, and a pair of feedback loops cross-connectedbetween said unidirectional selective element outlet ports and 'saidbistable element outlet ports.

3. The device as claimed in claim 2 further including -a pull-type diodeconnected between said pulse count inlet means and said unidirectionalselective element inlet to allow said fluid pulse count to be receivedby said unidirectional selective element but prevent flow from saidunidirectional selective element to said previous counter stage.

4. A device as claimed in claim 2 further including pilltype diodes andmeans for connecting said diodes between said unidirectional selectiveelement outlet ports and said I bistable element control ports with saiddiodes allowing fluid passage from said unidirectional selective elementto said bistable device but block flow in the opposite direction.

5. The device as claimed in claim 2 further including improved pill-typediodes and means to connect said diodes within said respective feedbackloops to prevent fluid flow from said pill-type unidirectional selectiveelement directly to said bistable element outlet ports but to freelyallow feedback from said outlet ports to said unidirectional selectiveelement.

6. The device as claimed in claim 2 wherein said pills are hollow toprovide maximum inertial restraint and the ends of said slots of each ofsaid pill-type fluidic elements are rounded to ensure complete fluidblocking when said pill is in fluid blocking position.

7. An improved pill-typefiuidic reversible counter stage comprising: asimple binary counter including first and second counter outlet portswhich alternatively receive said counter power streams, means to deliverfluid pulse counts from the previous; counter stage to said simplebinary counter, said reversible counter stage further comprising firstand second pill-type NANDS, means for supplying a first biasing fluid tothe NANDS for passage to said NAND outlet, each of said NANDS includinga pilltype NAND segment receiving a continuous up or down mode signal, aNAND segment receiving a pulsecoinciding with pulse delivery to thesimple binary counter from the previous count stagea'nd a NAND segmentreceiving the power stream outlet from the simple binary counter, commonfluid connecting means to the outlets of both NANDS whereby a pulsecount transfers to said next stage only under the conditions in whichthere is no pulse delivery from the previous stage, no power stream fromthe simple binary counter and no continuous mode signal.

8. The reversible counter as claimed in claim 7 further including apill-type high gain inverter-buffer connected to said common NAND outletto provide output power gam.

9. The device as claimed in claim 7 further including a second source ofrelatively high flow biasing fluid, means normally connecting saidsecond biasing fluid source to a pulse count outlet line for delivery tothe next counter stage and a high gain pill-type inverter-buiferconnected between said second biasing pressure source and said outletforming a flow pulse amplifier and having a control port coupled to saidcommon NAND outlet whereby in the presence of said first biasing fluidwithin said common NAND outlet, said high gain inverter-buffer acts toblock fluid passage from said second high pressure biasing sourceto saidreversible pulse count outlet.

10. The device as claimed in claim 7 wherein said simple binary countercomprises a Coanda type bistable fluid amplifier having a pill-typeunidirectional selective element between the previous counter stageinlet port and the Coanda control means.

11. The device as claimed in claim 10 further including a pulse countoutput means including a pill-type inverterbuffer having a high pressurefluid biasing inlet in line with the outlet port, and a control portcoupled to said common NAND outlet.

12. The device as claimed in claim 10 further including means connectinga Coanda type fluid amplifier between each of said NANDS and saidreversible counter pulse output means with one of said Coanda controlports in fluid connection with a NAND outlet port and one of the outputlegs of each bistable Coanda type amplifier in fluid connection with thecontrol port of said pulse flow amplifier with said other leg beingvented to the atmosphere.

13. An improved Coanda type fluid amplifier including a supply port fordirecting a power stream into a V-shaped chamber for selective deliveryto respective outlet legs, and a pair of control ports at right anglesto the power stream for receiving control signals tending to flip saidstream from one outlet leg to the other, the improvement comprising: acount pulse inlet; a pill-type inidirectional selective elementpositioned between said count pulse inlet and said control ports forconnecting said pulse inlet to a selected one of said control ports inaccordance with the position of said element; and feedback meansconnected between said outlet legs and said unidirectional selectiveelement for changing the position of said element upon the terminationof a count pulse.

14. The device as claimed in claim 13 wherein said feedback meanscomprises means for coupling positive pressure from each of said outletlegs to the corresponding side of said unidirectional selective element.

15. The device as claimed in claim 13 wherein said feedback meanscomprises means for coupling a reduced pressure from each of said outletlegs to the opposite side of said unidirectional selective element.

References Cited UNITED STATES PATENTS 3,114,390 12/1963 Glattli 235-2013,199,782 8/1965 Shinn 235--201 3,306,539 2/ 1967 Grirnland 235-201RICHARD B. WHJKINSON, Primary Examiner. LAWRENCE R. FRANKLIN, AssistantExaminer.

